How to locate and replace special characters in an XML file with Visual C# .NET

We can use the SecurityElement.Escape method to replace the invalid XML characters in a string with their valid XML equivalent. The following table shows the invalid XML characters and their respective replacements

Character Name	Entity Reference	Character Reference	Numeric Reference
Ampersand	&	&	&
Left angle bracket	<	<	<
Right angle bracket	>	>	>
Straight quotation mark	"	"	'
Apostrophe	'	'	"

Sample Usage of this Escape method.

//Usage
srtXML = SecurityElement.Escape(strXML);
  

For this you need to import System.Security namespace. Alternatively you can also use this simple replace method with all special characters in a single method like below

public string EscapeXml(string s)
{
    string toxml = s;
    if (!string.IsNullOrEmpty(toxml))
    {
        // replace special chars with entities
        toxml = toxml.Replace("&", "&");
        toxml = toxml.Replace("'", "'");
        toxml = toxml.Replace("\"", """);
        toxml = toxml.Replace(">", ">");
        toxml = toxml.Replace("<", "&lt;");
    }
    return toxml;
}
  

Hope this is useful!